The present invention relates to data processing systems, and more particularly to backup power systems for data processing systems.
Data processing systems often have a processing unit such as a central processing unit, microprocessor, or hardwired logic circuit and are usually operated with DC (direct current) power which is converted from AC (alternating current) power. Data processing systems, or data processors, also often have one or more memory circuits for storing information, and many types of these memory circuits require an uninterrupted supply of power to maintain the information stored within them. Thus, it is necessary to provide backup power systems to supply DC power to the data processors in the event the AC power fails or the data in the memory circuits can be lost.
Prior backup power systems have included an array of batteries that supply DC power to the data processor at a voltage level sufficient to operate the data processor. These prior systems have often suffered in that the batteries were exhausted after a relatively short time while supplying this relatively high DC voltage level to the data processor. To provide a backup power system that would supply power for a reasonable time, it was necessary to use relatively large batteries. While these batteries provided the necessary power, they were often physically large and bulky. Other backup systems merely provided a lower voltage power that would only supply power to the memory so that data would not be lost. This precluded operation of the data processor to enable an operator to retrieve important information from the memory.
Accordingly, it is an object of the present invention to provide a backup power system that does not have the above mentioned undesirable attributes.
Another object of the present invention is to provide an improved backup power system that utilizes a number of small batteries to supply power at a lower voltage to maintain data in memory and is also capable of supplying power at higher operating voltages for running the data processor for short periods so that data can be retrieved.